The present invention relates to a storage apparatus for commoditizing data to be stored in a storage device by transmitting and receiving this data to and from other storage apparatus; a storage system provided with this device; a data management method for operation of this system; and a controller execution program for control of the storage apparatus.
A storage apparatus is generally a single hard disk device or a disk array device for controlling a collection of plural hard disk devices by use of a control unit.
In recent years, iSCSI (internet SCSI), which is a protocol technology for realizing a SCSI process as a higher protocol on a TCP (Transmission Control Protocol)/IP, which is a network protocol, has been noted as a storage interface (hereinafter, abbreviated as I/F). According to the iSCSI, long-distance communication is available by using an IP network, and the iSCSI has a characteristic such that its application is cheaper than that of a FC (Fibre Channel) that has been conventionally used.
Therefore, when the iSCSI is used for communication between a host and a storage apparatus, a data sharing system can be constructed at a low price. For example, as this sort of technology, there is a known technology in which replication of the data of a storage apparatus A allocated at a branch A in a certain city is held in a storage apparatus B allocated at a branch B in another city so as to synchronize the data periodically. In addition, JP-A-2003-131917 discloses a method which is used to manage a difference in order to rapidly realize coincidence of remote copy data between remaining sites after an arbitrary site is struck among the storage apparatuses arranged at N sites (not less than three sites).